The Effect of Intrauterine Myelomeningocele Repair on the Incidence of Shunt-Dependent Hydrocephalus

Background: Intrauterine myelomeningocele repair (IUMR) was first successfully performed in 1997. Preliminary reports suggest that this procedure reduces the incidence of shunt-dependent hydrocephalus when compared to conventional postnatal therapy. However, the existing cohort of IUMR patients has not yet been systematically compared to a comparable group of conventionally treated controls. Methods: Patients 1 year old or greater who had undergone IUMR at either Vanderbilt University or the Children’s Hospital of Philadelphia (CHOP) were compared to a group of conventionally treated historical controls treated and followed at CHOP. In order to measure any differences between the groups, patients were stratified according to the level of the myelomeningocele lesion and the gestational age at the time of IUMR. Results: One hundred and four IUMR patients were compared to 189 conventionally treated controls. IUMR resulted in statistically significant reductions in the incidence of shunt-dependent hydrocephalus at both lumbar and sacral lesion levels. When lumbar lesion levels were further stratified, from L1 to L5, it appeared that the benefit of IUMR was statistically significant only at levels below L2. Other factors with a significant impact on hydrocephalus were estimated gestational age and ventricular size at the time of surgery. In particular, statistically significant differences compared to controls were seen in the younger (≤25 weeks) group but not in the older (>25 weeks) group. Conclusions: IUMR appears to substantially reduce the incidence of shunt-dependent hydrocephalus when compared to conventional treatment even when lesion level is taken into account. Patients with lesions above L3 may not share in this benefit. IUMR cannot be justified in fetuses older than 25 weeks of gestation. Additional improvements might be obtained by further reducing the average age at which fetuses are operated upon. It remains to be determined whether this benefit outweighs the potential risks of intrauterine surgery.